Question

I have a problem with @Autowired inside bean. I’ve posted simplified code structure. I have two classes annotated with @Configuration and two simple beans. In class D autowired bean doesn’t injected. So I wonder is it posible to solve the NPE without changing structure?

Class A:

@Configuration
public class A {

    @Autowired
    private B b;

    @Bean
    publict Other other() {
        b.doFoo();
        Other other = new Other();
    }

    @Bean
    public C c() {            
        return new C();
    }
}

Class B:

@Configuration
public class B {

    @Bean
    public D d() {
        return new D();
    }

    public void doFoo() {
        d().doBar();
    }
}

Class C inner structure of doesn’t matter. So class D:

public class D {

    @Autowired
    C c;

    public void doBar() {
        c.doFooBar(); // And here we got NPE
    }
}

I’s must be noticed, that if I move initialization of bean D from B to A and autowired it to B everything works fine:

@Configuration
public class A {

    @Autowired
    private B b;

    @Bean
    publict Other other() {
        b.doFoo();
        Other other = new Other()
    }

    @Bean
    public C c() {            
        return new C();
    }

    @Bean
    public D d() {
        return new D();
    }
}

@Configuration
public class B {

    @Autowired
    private D d;

    public void doFoo() {
        d.doBar();
    }
}

But this method doesn’t suit.

Answer 1

Let’s analyze class B for second. In that class when you call doFoo() method you have executed d().doBar();, which is like you manually created instance of class D, without any Spring. You called d() method directly it is just like you putted new D().doBar(). If you want to D be created with spring add this in class B:

@Autowired
private D d;

and change your method doFoo() to:

d.doBar();

Key part in your question was:

and autowired it to B everything works fine

This is also an answer.